linux-kernel - Re: [PATCH V3 3/3] mfd: palmas: Add support for optional wakeup

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Message-ID: <20141114170816.GW26481@atomide.com>
Date:	Fri, 14 Nov 2014 09:08:17 -0800
From:	Tony Lindgren <tony@...mide.com>
To:	Felipe Balbi <balbi@...com>
Cc:	Thomas Gleixner <tglx@...utronix.de>, Nishanth Menon <nm@...com>,
	lee.jones@...aro.org, LKML <linux-kernel@...r.kernel.org>,
	devicetree@...r.kernel.org, Keerthy <j-keerthy@...com>,
	Mark Brown <broonie@...aro.org>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	linux-omap@...r.kernel.org,
	LAK <linux-arm-kernel@...ts.infradead.org>,
	Kevin Hilman <khilman@...aro.org>
Subject: Re: [PATCH V3 3/3] mfd: palmas: Add support for optional wakeup

* Felipe Balbi <balbi@...com> [141114 08:20]:
> On Thu, Nov 13, 2014 at 09:40:31AM -0800, Tony Lindgren wrote:
> > +/**
> > + *	handle_wakeirq_thread - call device runtime pm calls on wake-up interrupt
> > + *	@wakeirq: device specific wake-up interrupt
> > + *	@dev_id: struct device entry
> > + */
> > +irqreturn_t handle_wakeirq_thread(int wakeirq, void *dev_id)
> > +{
> > +	struct device *dev = dev_id;
> > +	irqreturn_t ret = IRQ_NONE;
> > +
> > +	if (pm_runtime_suspended(dev)) {
> > +		pm_runtime_mark_last_busy(dev);
> > +		pm_request_resume(dev);
> 
> this assumes that every driver's ->resume() callback has a:
> 
> 	if (pending)
> 		handle_pending_irqs();
> 
> which might not be very nice. I'd rather follow what Thomas suggested
> and always pass device irq so this can mark it pending. Keep in mind
> that we *don't* need a pm_runtime_get_sync() in every IRQ handler
> because of that. Adding it is but the easiest way to get things working
> and, quite frankly, very silly.
> 
> what we want is rather:
> 
> 	irqreturn_t my_handler(int irq, void *dev_id)
> 	{
> 		struct device *dev = dev_id;
> 
> 		if (pm_runtime_suspended(dev)) {
> 			pending_irqs_to_be_handled_from_runtime_resume = true;
> 			pm_runtime_get(dev);
> 			clear_irq_source(dev);
> 			return IRQ_HANDLED;
> 		}
> 	}
> 
> or something similar.

Yeah I'll take a look.
 
> > +		ret = IRQ_HANDLED;
> > +	}
> 
> you're not masking the wake irq here which means that when this handler
> returns, wake irq will be unmasked by core IRQ subsystem leaving it
> unmasked after ->resume().

It currently assumes the consumer driver takes care of it. But I get
your point, we should be able to automate this further.

And right now there's also a dependency on dev->power.irq_safe so
RPM_ASYNC is not set. And this all should ideally work even with runtime
PM not set as it's also needed for resume from suspend.
 
> you *know* you'll pass a NULL top half handler, why don't you just force
> IRQF_ONESHOT instead of erroring out ? Just add:
> 
> 	wakeflags |= IRQF_ONESHOT;
> 
> and get it over with :-)

Good point :)
 
Regards,

Tony
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